Abstract
The management of the left subclavian artery (LSA) revascularization during aortic arch surgery is controversial and often challenging, especially during an emergency life-saving procedure. We report on a case of a 64-year old man, admitted to our institution with a Type A acute aortic dissection who underwent a frozen elephant trunk procedure with debranching of the supra-aortic vessels completed with an LSA revascularization using the in situ left internal mammary artery.
Keywords: Great vessels, Thoracic aorta, Left subclavian artery revascularization
INTRODUCTION
The management of the left subclavian artery (LSA) during aortic arch surgery is controversial and often challenging, especially during emergency life-saving procedures, such as a Type A aortic dissection [1]. Even if LSA revascularization is recommended by the Society for Vascular Surgery practice Guidelines [2], evidence-based data supporting these recommendations are still missing and it is not always possible.
The techniques currently used for LSA revascularization are: direct revascularization (end-to-end anastomosis), carotid-subclavian artery bypass and aorto-subclavian/axillary bypass. In this case, we report on a novel technique to revascularize the LSA during frozen elephant trunk (FET) with concomitant aortic arch debranching. After the harvesting of the left internal mammary artery (LIMA) as a conventional coronary artery bypass grafting operation, we anastomosed the in situ LIMA graft to the branched ascending aorta prosthesis and we closed the origin of the LSA with a direct suture with consequent blood ‘Backflow’ LIMA to LSA (Fig. 1 ).
Figure 1:
Schematic view of the operation (final result) .
CASE REPORT
A 64-year old man was admitted to our hospital with a diagnosis of Type A (DeBackey type I) acute aortic dissection and so underwent emergency surgery. The preoperative computed tomography (CT) scan showed that the primary intimal tear was identified in the arch, so we opted for an aortic arch debranching procedure associated with an FET.
Cardiopulmonary bypass (CPB) was instituted with right axillary artery (RAA) and right atrium cannulation. Active cooling was started to a bladder temperature of 25°C. After the direct aortic cross-clamping and myocardial cardioplegic arrest, the aortic valve was replaced, using a 25-mm stentless Medtronic Freestyle® bioprosthesis (Medtronic, Inc., Minneapolis, MN, USA). Then, the proximal anastomosis was performed between a Vascutek® Gelweave™ Lupiae Branched Arch Graft 30/10/10/8 (Vascutek, Terumo), the aortic valve bioprosthesis and the native aortic wall (inclusion technique), being careful to give the right angle to the prosthesis, tilting the branches of the anonymous trunk and common carotid artery towards the superior vena cava. Once the target bladder temperature of 25°C was reached, CPB flow was reduced. The innominate trunk was clamped and the right carotid artery was perfused through the cannula placed in the RAA (8 ml/kg/min). A separate cannula placed directly in the left carotid artery (LCA) provided its perfusion at 5 ml/kg/min. The innominate trunk and LCA were transected 1 cm from their origin. The aortic arch was resected 2 cm from the origin of the LSA. Then, a 28-mm E-vita OPEN PLUS stent graft system (Jotec®, Inc., Hechingen, Germany) was inserted into the true lumen of the descending aorta over a rigid guidewire and deployed with a pullback mechanism. The incorporated Dacron graft was drawn out and then sutured to the transected distal arch. The distal anastomosis was performed between the Lupiae™ Branched Arch Graft, the cuff of the E-vita prosthesis and the native aortic arch wall (ischaemic time 33 min). We proceeded with de-airing of the heart and of the vascular prosthesis. The systemic perfusion was then antegradely restored through the side branch of the graft. We then performed debranching of the LCA and of the innominate trunk. Selective antegrade cerebral perfusion (SACP) from the RAA was then stopped.
Because of the unfavourable anatomy and friability of the arterial wall, direct LSA revascularization was not possible, so we proceeded with LIMA harvesting during the rewarming time and we performed an anastomosis between the in situ LIMA and the branch of the ascending aortic Lupiae prosthesis, using a polypropylene 7/0 suture. Finally, we closed the origin of the LSA with a direct suture and the correct opening of the stent graft was controlled using transesophageal echocardiography. Transit time flow measurement of the LIMA graft was 150 ml/min.
CPB, SACP, lower body circulatory arrest and myocardial ischaemic time were 314, 53, 33 and 122 min, respectively.
The postoperative course was uneventful and the patient was discharged from the hospital on the 10th postoperative day. The Δ arterial pressure, left arm versus right arm, was 20 mmHg. The postoperative duplex scan showed good flow, but slightly lower flow velocity in the LSA versus the right subclavian artery. The transcranial Doppler showed an antegrade flow in the left vertebral artery. Angio-CT scan 12 months after the operation showed the patency of all vessels involved (innominate trunk, LCA, LIMA, LSA and left vertebral artery) (Fig. 2). The LIMA size increased from 3.2 to 5.3 mm.
Figure 2:
Postoperative (12 month) images of the aorta 3D CT reconstruction image of the thoracic aorta, showing the patency of the innominate trunk, the LCA, the LSA, the LIMA graft and the left vertebral artery. LIMA: left internal mammary artery; LCA: left carotid artery; LSA: left subclavian artery; CT: computed tomography.
Eighteen months after the operation, the patient is symptomless and has left upper limb circulation as well.
DISCUSSION
The LSA revascularization during arch surgery is recommended by the Society for Vascular Surgery practice Guidelines. Even if it is suggested whenever possible, these recommendations are still missing [2]. The ‘gold standard’ procedures for LSA revascularization are: direct revascularization (end-to-end anastomosis), carotid-subclavian artery bypass and aorto-subclavian bypass [3–5]. In some cases, these techniques are not always feasible because of unfavourable anatomy, calcifications, anomalous origin and because they are technically demanding, especially for inexperienced surgeons and during emergency surgery. In some cases, the LSA can be simply covered and eventually revascularized later. However, the acute covering of the LSA has some potential complications, such as stroke, spinal cord ischaemia, arm ischaemia and vertebral insufficiency. Therefore, in this particular case, because of unfavourable anatomy, especially because of LSA depth and left axillary artery fragility, we decided to perform a bypass between the prosthesis of the ascending aorta and the LSA using the LIMA in situ thus achieving a ‘backflow’. The decision to use the LIMA was taken during the operation, as a bail-out option, when we realized that a direct revascularization was not feasible. To minimize the loss of CPB time, the LIMA was harvested during the rewarming time; then it was grafted to one of the side branches of the Lupiae graft. It was not necessary to harvest the LIMA in its entire length. We believe that stopping 4 cm before the arterial bifurcation is sufficient to use it in this way. To the best of our knowledge, this is the first reported case in which the LIMA is used for this purpose.
In conclusion, this case shows that LSA revascularization using the LIMA anastomosed to the ascending aorta to achieve blood ‘backflow’ during FET with arch debranching is technically feasible and seems easy and reproducible especially in an emergency setting and it can be an alternative when other techniques are not a possibility. Surgeons should weight the benefit of LSA prophylactic revascularization during a life-saving operation, taking into consideration the potential surgical risks, such as increasing CPB time and bleeding risk. Further follow-up data are needed to assess the long-term safety and efficacy of this novel technique.
Conflict of interest: none declared.
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